Load independent thermo-magnetic flasher

ABSTRACT

A thermomagnetic flasher having a main pull-wire controlled armature to make and break a first contact pair, an auxiliary armature extending from the main armature to make and break a second contact pair, and an electromagnetically-controlled armature to make and break a third contact pair. During heating of the pull wire, the contact pairs close in second-first-third order, and during cooling of the pull wire, the contact pairs open in first-second-third order. The second and third contact pairs control a load current path paralleling the path controlled by the first contact pair. In the foregoing cycle, during heating of the pull wire, the path through the first contact pair closes first to energize the load, and the path through the second and third contact pairs closes second. During cooling of the pull wire, the path through the first contact pair opens first, but the load is still energized by the path through the second and third contact pairs, which opens second.

United States Patent [72] Inventor liemntlagG.Sllherg Summlt.NJ. [21]AppLNo. 869.551 1221 Filed 0ct.27,1969 [45] Patented July 13,1971 [73)Assignee Wagner Electric Corporation 54] LOAD INDEPENDENTTHERMO-MAGNETIC FLASIIER 9 Claltaa,1 Drawlng Fig. 152] 335/141 151]1at.Cl................ ..1I01lt61/06 [50] FieldolSearch 335/141. 143.144, 145.146

[56] letereaeetClted UNITED STATES PATENTS 2,103,276 12/1937Schmidinger................. 335/141 2.673.931 3/1954 ilolliru 335/141X2.674.130 4/1954 Klebanolf 335/141X 3.400.346 9/1968 Parkea........335/141 2,503,303 4/1950 Sitzer 335/143 Primary Examiner-Harold BroomeAttorney- Eyre. Mann 8: Lucas ABSTRACT: A thennornagnetic flasher havinga main pull wire controlled armature to make and break a first contactpair. an auxiliary armature extending from the main armature to make andbreak a second contact pair. and an electromagnetically-controlledarmature to make and break a third contact pair. During heating of thepull wire, the contact pair: close in tecond-fint-third order. andduring cooling of the pull wire, the contact pair: open infirat-second-third order. The second and third contact pain control aload current path paralleling the path controlled by the first contactpair. In the foregoing cycle. during heating of the pull wire, the paththrough the first contact pair closes first to energize the load, andthe path through the second and third contact pairs closes second.During cooling of the pull wire. the path through the tint contact pairopens firat, but the load is still energized by the path through thesecond and third contact pain, which opens aecond.

LOAD INDEPENDENT THERMO-MAGNETIC FLASHER The present invention relatesto a flasher unit employing thermally and magnetically generated forcesin its operation. More specifically, a pull wire is employed to controla main armature and an auxiliary armature attached thereto, while anelectromagnet is employed to control a third armature.

The flasher unit embodying the present invention has numerousadvantages. This unit can replace both shunt and series-type flashers,is capable of directional and emergency signalling, and can provide apositive pilot indication over a wide range ofloads. The ON time isalmost exclusively a function of the cooling rate of the pull wire, andthe speed (rate) adjustment is independent of the ratio adjustment.Also, contact breaking speed is sufficiently high to enable the use ofrelatively low-cost contact material.

The invention may be better understood by reference to the accompanyingdrawing, ofwhich:

FIG. l is a diagram of the preferred embodiment of the flasher unitshowing the electrical and mechanical features thereof, and the mannerin which the flasher unit is connected to external circuitry.

Referring to FIG. I, the flasher unit comprises a main armature 12 whichis attached to a rigid support member 14 by a leaf spring 16. Mainarmature 12 has an extension 18 to which one end of pull wire 20 ismechanically and electrically connected. The other end of pull wire 20is secured by an insulating glass bead 22 set in a mechanical support24. The pull wire 20 is connected in series with a ballast resistor 26,one terminal of which is connected to fixed contact 28, which is in acooperative make-and-break relationship with movable contact 30 mountedon main armature 12. Pull wire 20 maintains contacts 28 and 30 normallyopen against the bias of leaf spring 16.

Mechanically and electrically connected to main armature 12 is aflexible auxiliary armature 32 which is slaved to the motion of mainarmature l2 and serves to control the making and breaking of fixedcontact 34 and movable contact 36 mounted on the auxiliary armature 32.An essential feature of the present invention is that the gap betweenthe normally open contacts 28 and 30 must be greater than the gapbetween the normally open contacts 34 and 36, so that the latter pair ofcontacts willclose first upon heating of the pull wire 20.

A third armature 38 is mounted to fixed support 40 by means of a leafspring 42, which biases the armature 38 so that the fixed and movablecontacts, 44 and 46 respectively, are normally open. Contacts 44 and 46close when there is a sufficiently strong magnetic force exerted onarmature 38 by coil 48 and magnetic core 50, which, like core 52, isU-shaped. Cores 50 and 52 may also be integrally formed in the shape ofan l" laid on its side (as it would appear in the drawing). Coil 48 andmagnetic core 52 serve to exert an attracting electromagnetic force onmain armature l2 and auxiliary armature 32 during a portion of theoperating cycle of the flasher unit. Fixed contact 44 is connected tofixed contact 34, and movable contact 46 is connected through armature38 to fixed contact 28. The coil 48 is connected between fixed contact28 and the load terminal 54. Battery terminal 56 is connected throughmechanical mount 14, leafspring l6, and main armature l2 to movablecontact 30; through the mount 14, spring 16 and the auxiliary armature32 to movable contact 36; and through the mount 14, spring l6, mainarmature 12, pull wire 20, and ballast resistor 26 to fixed contact 28.

The external circuitry to which the flasher unit is connected consistsof battery 8, which is connected to battery ter' minal 56, and load Lwhich is connectable through switch S to load terminal 54.

The operation ofthe flasher unit is as follows:

When switch S is closed, a small current will flow from battery Bthrough battery contact 56, spring 16, main armature 12, its extension18, pull wire 20, ballast resistor 26, coil 48 and load terminal 54through switch S and load L. Where load L is a lamp load. this currentis sufficiently small to prevent the lamps from becoming incandescent.As this current passes through pull wire 20, thereby causing same toheat and expand, main armature 12 and auxiliary annature 32 begin tomove downward. As this motion progresses, contacts 34 and 36 closefirst. However, this event has no immediate effect, since contacts 44and 46 are still open, thus holding open the portion of the circuit fromcontact 34 to ground. After contacts 34 and 36 have closed, mainarmature l2 continues to travel downward until contacts 28 and 30 close,thus energizing the load L. Current now flows from battery B throughterminal 56, spring l6, main armature 12, contacts 28 and 30, throughcoil 48, terminal 54, switch S and load L to ground, thereby creatingmagnetic fields in cores $0 and 52. The field generated in core 52exerts a magnetic attraction on main armature 12 to aid the force ofleafspring 16 in maintaining contacts 28 and 30 closed. The magneticfield in core 50 attracts armature 38, thereby causing contacts 44 and46 to close substantially simultaneously with the closing of contacts 28and 30. The portion of the load current path comprising main armature l2and contacts 28 and 30 connected between leaf spring 16 and the highside of coil 48 is now paralleled by auxiliary armature 32, contacts 34and 36, contacts 44 and 46, and armature 38 connected between the samepoints. Heating current is now shunted from pull wire 20, which beginsto cool. As pull wire 20 contracts, it exerts sufficient force on themain armature 12 to overcome the magnetic attraction of the fieldgenerated in core 52, thus causing contacts 28 and 30 to break, but loadcurrent continues to flow through auxiliary armature 32, contacts 34 and36, contacts 44 and 46, armature 38 and coil 48. Since the magneticfield ofcoil 48 is thus maintained, there is no inductively generatedvoltage to cause arcing across contacts 28 and 30 when they open. As themain armature l2 moves upward, it engages auxiliary armature 32 andthereby causes contacts 34 and 36 to open. The breaking speed ofcontacts 34 and 36 is relatively high due to the camming action of mainarmature 12 on auxiliary armature 32. Also, at the time of theseparation of contacts 34 and 36, the field in core 52 collapses as aresult of the cessation of flow of load current through coil 48, thuseliminating the magnetic forces exerted on armatures l2 and 32 andfurther enhancing the breaking speed of contacts 34 and 36.Substantially simultaneously with the opening of contacts 34 and 36,contacts 44 and 46 also open as a result of the collapse of the magneticfield which serves to attract armature 38 to core 50. Heating currentagain begins to flow through pull wire 20 as described earlier, and theforegoing cycle will continue to repeat itself as long as switch S isclosed.

The advantages of the present invention, as well as certain changes andmodifications to the disclosed embodiment thereof, will be readilyapparent to those skilled in the art. It is the applicant's intention tocover all those changes and modifications which could be made to theembodiment of the invention herein chosen for the purposes of thedisclosure without departing from the spirit and scope of the invention.

1 claim:

I. A two-terminal thermomagnetic flasher unit comprising:

l. first and second terminals;

2. first circuit-controlling means operative to close and open a firstload current path; and

3. second circuit-controlling means operative in cooperation with saidfirst circuit control means to close and open a second load current pathwhich is partially in parallel and partially coincident with said firstload current path between said first and second terminals, said firstand second circuit-controlling means being jointly operative, when asource of direct-current power and a load are connected in seriesbetween said first and second terminals, sequentially to close saidfirst load current path, to close said second load current path, to opensaid first load current path, and to open said second load current pathduring each flashing cycle.

2. A thermomagnetic flasher unit according to claim 1 wherein:

1. said first circuit-controlling means comprises a. a main armaturehaving a first movable contact mounted thereon in cooperativemake-and-break relationship with a first fixed contact;

b. mounting means for said main armature;

c. a pull wire connected to said main armature for controlling theposition thereof; and

d. electromagnetic means operative when energized to exert an attractivemagnetic force upon said armature.

3. A thermomagnetic flasher unit according to claim 2 wherein a ballastresistor is connected between said pull wire and said first fixedcontact.

4. A thermomagnetic flasher unit according to claim 2 wherein saidmounting means includes a leaf spring operative to bias said firstcontacts toward a closed position.

5. A thermomagnetic flasher unit according to claim 2 wherein:

I. said second circuit-controlling means comprises a. a flexibleauxiliary armature attached to said main armature and having a secondmoveable contact mounted thereon in cooperative make-andbreakrelationship with a second fixed contact, the gap between said firstcontacts being greater than the gap between said second contacts; and

b. relay means including a coil in common with said electromagneticmeans and operative when energized to close a current path between saidsecond fixed contact and said first terminal.

6. A thermomagnetic flasher unit according to claim 5 wherein said coilis connected between said first fixed contact and said first terminal,and disposed about at least one magnetizable core member.

7. A thermomagnctic flasher unit according to claim 6 wherein said coilis disposed about first and second U-shaped magnetizable cores, saidfirst core being operatively associated with said main and auxiliaryarmatures and said second core being an element ofsaid relay means.

8. A thermomagnetic flasher unit according to claim 5 wherein said relaymeans further comprises an armature having a third movable contactmounted thereon in cooperative make-and-break relationship with a thirdfixed contact. said relay means being operative when energized to closea path between said second fixed contact through said coil to said firstterminal.

9. A thermomagnetic flasher unit comprising:

1. a main armature, a movable contact mounted thereon, and a fixedcontact in cooperative malte-and-break relationship with said movablecontact;

2. mounting means for said main armature connected to a first terminalof said flasher unit and operative to urge said first contacts to aclosed position;

3. a pull wire attached at one end to said main armature and connectedto said fixed contact, said pull wire, when cool, maintaining said firstcontacts normally open;

4. means for fixedly securing the other end of said pull wire;

. a ballast resistor connected between said pull wire and said firstfixed contact;

6. an auxiliary armature connected to said main armature, a movablecontact mounted thereon and a fixed contact in cooperativemake-and-break relationship with said movable contact, said auxiliaryarmature contacts being set with a smaller gap than said main armaturecontacts;

. an electromagnetic relay including a coil, first and secondmagnetizable cores, an armature controlled by the magnetic forcesexerted by said second core in response to current through said coil, amovable contact mounted on said armature, and a fixed contact incooperative makeand-brealt relationship with said movable contact, oneterminal of said coil being directly connected to said first fixedcontact, said relay being operative to make and break a current pathbetween said one terminal of said coil and said second fixed contact,the other terminal of said coil being connected to a second terminal ofsaid flasher unit, and said second core being operative in response tothe current flowing through said coil to exert magnetic forces upon saidmain and auxiliary armatures.

LII

1. A two-terminal thermomagnetic flasher unit comprising:
 1. first andsecond terminals;
 2. first circuit-controlling means operative to closeand open a first load current path; and
 3. second circuit-controllingmeans operative in cooperation with said first circuit control means toclose and open a second load current path which is partially in paralleland partially coincident with said first load current path between saidfirst and second terminals, said first and second circuitcontrollingmeans being jointly operative, when a source of direct-current power anda load are connected in series between said first and second terminals,sequentially to close said first load current path, to close said secondload current path, to open said first load current path, and to opensaid second load current path during each flashing cycle.
 2. mountingmeans for said main armature connected to a first terminal of saidflasher unit and operative to urge said first contacts to a closedposition;
 2. A thermomagnetic flasher unit according to claim 1 wherein:2. first circuit-controlling means operative to close and open a firstload current path; and
 3. A thermomagnetic flasher unit according toclaim 2 wherein a ballast resistor is connected between said pull wireand said first fixed contact.
 3. second circuit-controlling meansoperative in cooperation with said first circuit control means to closeand open a second load current path which is partially in parallel andpartially coincident with said first load current path between saidfirst and second terminals, said first and second circuit-controllingmeans being jointly operative, when a source of direct-current power anda load are connected in series between said first and second terminals,sequentially to close said first load current path, to close said secondload current path, to open said first load current path, and to opensaid second load current path during each flashing cycle.
 3. a pull wireattached at one end to said main armature and connected to said fixedcontact, said pull wire, when cool, maintaining said first contactsnormally open;
 4. means for fixedly securing the other end of said pullwire;
 4. A thermomagnetic flasher unit according to claim 2 wherein saidmounting means includes a leaf spring operative to bias said firstcontacts toward a closed position.
 5. A thermomagnetic flasher unitaccording to claim 2 wherein:
 5. a ballast resistor connected betweensaid pull wire and said first fixed contact;
 6. an auxiliary armatureconnected to said main armature, a movable contact mounted thereon and afixed contact in cooperative make-and-break relationship with saidmovable contact, said auxiliary armature contacts being set with asmaller gap than said main armature contacts;
 6. A thermomagneticflasher unit according to claim 5 wherein said coil is connected betweensaid first fixed contact and said first terminal, and disposed about atleast one magnetizable core member.
 7. A thermomagnetic flasher unitaccording to claim 6 wherein said coil is disposed about first andsecond U-shaped magnetizable cores, said first core being operativelyassociated with said main and auxiliary armatures and said second corebeing an element of said relay means.
 7. an electromagnetic relayincluding a coil, first and second magnetizable cores, an armaturecontrolled by the magnetic forces exerted by said second core inresponse to current through said coil, a movable contact mounted on saidarmature, and a fixed contact in cooperative make-and-break relationshipwith said movable contact, one terminal of said coil being directlyconnected to said first fixed contact, said relay being operative tomake and break a current path between said one terminal of said coil andsaid second fixed contact, the other terminal of said coil beingconnected to a second terminal of said flasher unit, and said secondcore being operative in response to the current flowing through saidcoil to exert magnetic forces upon said main and auxiliary armatures. 8.A thermomagnetic flasher unit according to claim 5 wherein said relaymeans further comprises an armature having a third movable contactmounted thereon in cooperative make-and-break relationship with a thirdfixed contact, said relay Means being operative when energized to closea path between said second fixed contact through said coil to said firstterminal.
 9. A thermomagnetic flasher unit comprising: